As wireless communication becomes more and more popular, demand for high speed wireless communication has dramatically increased. Standards such as Universal Mobile Telecommunications System (UMTS) and High Speed Packet Access (HSPA) have been developed to meet this demand.
Signal quality of the receiver radio, or the receiver, in the subscriber station or the base station may have significant impact on the performance of the wireless communication. Wireless signals, as received by the antenna and passed through to the receiver, may contain various impairments, including noise and/or interference. Noise may include platform noises generated by the hardware platform, such as clocks and data buses of the subscriber station or the base station. Interference may result from other symbols of interest (inter-symbol interference), symbols intended for other users in the cell (intra-cell interference), or symbols intended for other users in other cells (inter-cell interference).
Certain communication systems may estimate noise based on an additive white Gaussian noise (AWGN) model, in which case the noise may be treated as a linear addition of wideband or white noise with a constant spectral density (often measured as watts per hertz of bandwidth) and a Gaussian distribution of amplitude. However, AWGN based noise model may be inadequate for communication systems in which noises caused by the hardware platform are significant.
Interference may be modeled based on the orthogonal nature of the wireless signals received by the receiver. For example, a generalized rake (G-Rake) receiver may be able to reduce the effect of interference on a received wireless signal by estimating interference and compensating for its impact. A G-Rake receiver may also estimate the noise of the received wireless signal based on the AWGN model. However, platform noises, which may include non-AWGN based noises, are neither modulated based on orthogonal codes nor based on a Gaussian distribution. As such, the current method of estimating interference and AWGN in traditional G-Rake receivers may not provide adequate compensation when the impairments caused by the platform noises are significant.
Platform noise may degrade receiver performance and make the equipment more difficult to pass carriers' certification test. As subscriber stations and base stations become more and more complex, the impact of platform noise to the receiver may become more and more significant.